The Free Fatty Acid (FFA) assay kit utilizes a series of enzyme reactions to measure free fatty acid levels in samples. First, Acyl-Coa synthetase attaches coenzyme A to the FFAs to form Acyl-Coa. Then, Acyl-Coa oxidase reacts with Acyl-Coa to produce hydrogen peroxide. The FFA level in the sample is determined by quantifying the hydrogen peroxide generated by the enzyme reaction with a fluorogenic probe that can be measured with a spectrophotometer.